1. Field of the Invention
The invention relates to a control apparatus constructed so that the behavior characteristic or acceleration/deceleration characteristic of a vehicle (hereinafter, referred to as travel characteristic), such as the vehicle's motive power characteristic, the steering characteristic, the suspension characteristic, etc., will be caused to agree with the travel environment of the vehicle, the driver's preferences and the driver's intentions in driving, etc.
2. Description of Related Art
The behavior of a vehicle, such as the vehicle speed, the traveling direction, etc., changes as the driver of the vehicle performs an accelerating/decelerating operation or a steering operation. The relationship between the amount of such operation and the amount of change in the behavior of the vehicle is determined not only by energy efficiency, such as fuel economy and the like, but also by the ride comfort and the quietness that are demanded of the vehicles as well as the motive power performance and the like.
On another hand, the environments where vehicles travel vary, including urban areas, express highways, winding roads, uphill roads, downhill roads, etc., and the impressions that the vehicle drivers receive from the vehicles also vary depending on the drivers' likings (inclinations) and the types of the vehicles. Therefore, if the environment of travel of a vehicle or the driver of the vehicle changes, an expected travel characteristic is not always obtained, so that so-called drivability sometimes declines.
Therefore, there has been developed a vehicle that allows manual selection of a desired one of travel characteristics regarding the vehicle behavior that include the motive power characteristic (or acceleration characteristic), the suspension characteristic, etc., through a mode switching operation. For example, one of such vehicles allows selection, through a switch operation, of a desired one of a sports mode in which the acceleration characteristic is excellent and the suspension setting is made to a hard side to a certain degree, a normal mode in which a relatively slow acceleration characteristic is given and a comparatively soft suspension characteristic is made, and an economy mode in which priority is given to the fuel economy, among other modes.
Furthermore, various apparatuses for reflecting the driving inclinations of drivers in the behavior control of a vehicle have been proposed. According to such apparatuses, the switch operation is unnecessary, and minute or fine changes of the characteristic of the vehicle are possible. An example of such apparatuses is described in Japanese Patent Application Publication No. 06-249007 (JP-A-06-249007). The apparatus described in Japanese Patent Application Publication No. 06-249007 (JP-A-06-249007) is a drive force control apparatus that learns a relationship of the acceleration of the vehicle with the accelerator stroke and the vehicle speed as a demanded acceleration model, and that computes a throttle opening degree on the basis of a deviation of the model from a second reference acceleration model that reflects the driver's inclination regarding the driving, and a deviation between the second reference acceleration model and a first reference acceleration model that is a standard model.
The foregoing apparatus described in Japanese Patent Application Publication No. 06-249007 (JP-A-06-249007) changes the settings for the driver's inclination about the driving or the vehicle's travel characteristic on the basis of the longitudinal acceleration of the vehicle or on the basis of the driver's operation of the accelerator pedal. Therefore, the driver's inclination about the driving can be estimated by detecting or estimating the behavior of the acceleration of the vehicle, and then can be reflected in the control of the vehicle behavior. However, there are still present rooms for improvement in order to reflect the environment of travel of a vehicle and the driver's preference and also intentions in the driving more accurately in the control of the vehicle behavior.